Systems and methods for signaling reference pictures in video coding

Abstract

According to an aspect of an invention, a method for signaling reference pictures in video coding is disclosed. The method comprises: decoding a number of entries in a reference picture list syntax structure; decoding a number of reference index active minus one syntax in a slice header, if the number of entries is greater than one; and deriving an active variable by using the number of reference index active minus one syntax.

The invention claimed is: 
     
         1 . A method of decoding video data, the method comprising:
 receiving a first reference picture list structure, wherein the first reference picture list structure is defined by a first value;   decoding a first number of entries syntax element in the first reference picture list structure, wherein the first number of entries syntax element specifies a number of entries in the first reference picture list structure;   receiving a second reference picture list structure, wherein the second reference picture list structure is defined by a second value;   decoding a second number of entries syntax element in the second reference picture list structure, wherein the second number of entries syntax element specifies a number of entries in the second reference picture list structure;   receiving a slice header;   decoding an override flag syntax element in the slice header, wherein the override flag syntax element specifies whether a number of reference index active minus one syntax element is present for at least one of a P slice and a B slice, in a case that (i) a slice type is not an I slice and the first number of entries syntax element is greater than one, or (ii) a slice type is a B slice and the second number of entries syntax element is greater than one; and   decoding (i) the number of reference index active minus one syntax element defined by the first value for the P slice or (ii) (a) the number of reference index active minus one syntax element defined by the first value and (b) the number of reference index active minus one syntax element defined by the second value for the B slice, in a case that the override flag syntax element is equal to one.   
     
     
         2 . A device comprising one or more processors configured to:
 receive a first reference picture list structure, wherein the first reference picture list structure is defined by a first value;   decode a first number of entries syntax element in the first reference picture list structure, wherein the first number of entries syntax element specifies a number of entries in the first reference picture list structure;   receive a second reference picture list structure, wherein the second reference picture list structure is defined by a second value;   decode a second number of entries syntax element in the second reference picture list structure, wherein the second number of entries syntax element specifies a number of entries in the second reference picture list structure;   receive a slice header;   decode an override flag syntax element in the slice header, wherein the override flag syntax element specifies whether a number of reference index active minus one syntax element is present for at least one of a P slice and a B slice, in a case that (i) a slice type is not an I slice and the first number of entries syntax element is greater than one, or (ii) a slice type is a B slice and the second number of entries syntax element is greater than one; and   decode (i) the number of reference index active minus one syntax element defined by the first value for the P slice or (ii) (a) the number of reference index active minus one syntax element defined by the first value and (b) the number of reference index active minus one syntax element defined by the second value for the B slice, in a case that the override flag syntax element is equal to one.   
     
     
         3 . The device of  claim 2 , wherein the one or more processors configured to:
 derive a variable by using the number of reference index active minus one syntax,   wherein the variable is set equal to a first value obtained by adding one to a value of the number of reference index active minus one syntax element, in a case that a value of the override flag syntax element is equal to a second value.   
     
     
         4 . The device of  claim 3 , wherein the variable is set equal an inferred value, in a case that a value of the first number of entries syntax element is greater than or equal to the inferred value. 
     
     
         5 . A method of coding data, the method including:
 signaling a first reference picture list structure, wherein the first reference picture list structure is defined by a first value, wherein the first reference picture list structure includes a first number of entries syntax element, wherein the first number of entries syntax element specifies a number of entries in the first reference picture list structure;   signaling a second reference picture list structure, wherein the second reference picture list structure is defined by a second value, wherein the second reference picture list structure includes a second number of entries syntax element, wherein the second number of entries syntax element specifies a number of entries in the second reference picture list structure; and   signaling a slice header, wherein the slice header includes:   an override flag syntax element, wherein the override flag syntax element specifies whether a number of reference index active minus one syntax element is present for at least one of a P slice and a B slice, in a case that (i) a slice type is not an I slice and the first number of entries syntax element is greater than one, or (ii) a slice type is a B slice and the second number of entries syntax element is greater than one, and   (i) the number of reference index active minus one syntax element defined by the first value for the P slice or (ii) (a) the number of reference index active minus one syntax element defined by the first value and (b) the number of reference index active minus one syntax element defined by the second value for the B slice, in a case that the override flag syntax element is equal to one.   
     
     
         6 . A device of coding data, the device comprising:
 one or more processors configured to:   signal a first reference picture list structure, wherein the first reference picture list structure is defined by a first value, wherein the first reference picture list structure includes a first number of entries syntax element, wherein the first number of entries syntax element specifies a number of entries in the first reference picture list structure;   signal a second reference picture list structure, wherein the second reference picture list structure is defined by a second value, wherein the second reference picture list structure includes a second number of entries syntax element, wherein the second number of entries syntax element specifies a number of entries in the second reference picture list structure; and   signal a slice header, wherein the slice header includes:   an override flag syntax element, wherein the override flag syntax element specifies whether a number of reference index active minus one syntax element is present for at least one of a P slice and a B slice, in a case that (i) a slice type is not an I slice and the first number of entries syntax element is greater than one, or (ii) a slice type is a B slice and the second number of entries syntax element is greater than one, and   (i) the number of reference index active minus one syntax element defined by the first value for the P slice or (ii) (a) the number of reference index active minus one syntax element defined by the first value and (b) the number of reference index active minus one syntax element defined by the second value for the B slice, in a case that the override flag syntax element is equal to one.